Reflective eyepiece optical system and head-mounted near-to-eye display device

ABSTRACT

The present invention relates to a reflective eyepiece optical system and a head-mounted near-to-eye display device. The system includes: a first optical element and a second optical element arranged successively along an incident direction of an optical axis of the human eye, and a first lens group located on an optical axis of an miniature image displayer. The first optical element reflects the image light refracted by the first lens group to the second optical element, and then transmits the image light reflected by the second optical element to the human eye. The effective focal lengths of the first sub-lens group, the second sub-lens group and the third sub-lens group are a combination of positive, negative and positive. The optical path is effectively folded, the overall size of the optical system is reduced, aberrations are largely eliminated, and a visual experience effect of high liveness is achieved.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application claims priority to Chinese patent application No. 202110879659.9, filed on Aug. 2, 2021, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the field of optical technology, and more particularly, to a reflective eyepiece optical system and a head-mounted near-to-eye display device.

BACKGROUND

With the development of electronic devices to ultra-miniaturization, head-mounted display devices and products are constantly emerging in military, industrial, medical, educational, consumption and other fields, and in a typical wearable computing architecture, a head-mounted display device is a key component. The head-mounted display device directs the video image light emitted from a miniature image displayer (e.g., a transmissive or reflective liquid crystal displayer, an organic electroluminescent element, or a DMD element) to the pupil of the user by optical technology to implement virtual magnified images in the near-eye range of the user, so as to provide the user with intuitive, visual images, video, text information. The eyepiece optical system is the core of the head-mounted display device, which realizes the function of displaying a miniature image in front of human eyes to form a virtual magnified image.

The head-mounted display device develops in the direction of compact size, light weight, convenient wearing, and load reduction. Meanwhile, a large field-of-view angle and visual comfort experience have gradually become key factors to evaluate the quality of the head-mounted display device. The large field-of-view angle determines a visual experience effect of high liveness, and high image quality and low distortion determine the comfort of visual experience. To meet these requirements, the optical system should try its best to achieve such indexes as a large field-of-view angle, high image resolution, low distortion, small field curvature, and a small volume. It is a great challenge for system design and aberration optimization to satisfy the above optical properties at the same time.

In Patent Document 1 (Chinese Patent Publication No. CN101915992A), Patent Document 2 (Chinese Patent Publication No. CN211698430U), Patent Document 3 (Chinese Patent Publication No. CN106662678A), and Patent Document 4 (Chinese Patent Publication No. CN105229514A), a reflective optical system utilizing a combination of traditional optical spherical surfaces and even-order aspherical face shapes is provided respectively, wherein Patent Document 1 adopts a relay scheme, but this scheme adopts a free-form surface reflection means, which greatly increases the difficulty of realizing the entire optical system; the optical systems in the Patent Document 2, Patent Document 3 and Patent Document 4 use reflective optical systems, but the basic optical structures vary greatly from one to another due to different application fields, such as in terms of a matching relationship between a lens face shape and a gap between the lenses.

Patent Document 5 (Chinese Patent Publication No. CN207081891U) and Patent Document 6 (Chinese Patent Publication No. CN108604007A) provide an eyepiece optical system that adopts a reflex means, which ensures high-quality imaging; however its optical structure is often limited to single lens reflection, thereby greatly limiting a performance ratio of the entire optical structure.

To sum up, the existing optical structures not only have problems such as heavy weight, small field-of-view angle, and insufficient optical performance, but also have problems such as difficulty in processing and mass production due to the difficulty of implementation.

SUMMARY

The technical problem to be solved by the present invention is that the existing optical structure has the problems of heavy weight, low image quality, distortion, insufficient field-of-view angle, and difficulty in mass production. Aiming at the above-mentioned defects of the prior art, a reflective eyepiece optical system and a head-mounted near-to-eye display device are provided.

The technical solutions adopted in the present invention to solve the technical problem thereof are as follows: constructing a reflective eyepiece optical system, including: a first optical element and a second optical element arranged successively along an incident direction of an optical axis of a human eye, and a first lens group located on an optical axis of a miniature image displayer; the first optical element is used for transmitting and reflecting an image light from the miniature image displayer; the second optical element includes an optical reflection surface, and the optical reflection surface is concave to the human eye; the first optical element reflects the image light refracted by the first lens group to the second optical element, and then transmits the image light reflected by the second optical element to the human eye;

an effective focal length of the eyepiece optical system is f_(w), an effective focal length of the first lens group is f₁, an effective focal length of the second optical element is f₂, and f_(w), f₁, f₂ satisfy the following relations (1), (2): f ₁ /f _(w)<−0.47  (1); −2.53<f ₂ /f _(w)<−0.64  (2);

the first lens group includes a first sub-lens group, a second sub-lens group and a third sub-lens group arranged coaxially and successively along the optical axis direction from an eye viewing side to the miniature image displayer side; the effective focal lengths of the first sub-lens group, the second sub-lens group and the third sub-lens group are a combination of positive, negative and positive; the effective focal length of the first sub-lens group is f₁₁, the effective focal length of the second sub-lens group is f₁₂, the effective focal length of the third sub-lens group is f₁₃, and f₁₁, f₁₂, f₁₃ and f₁ satisfy the following relations (3), (4), (5): 0.19<f ₁₁ /f ₁  (3); f ₁₂ /f ₁<−0.019  (4); 0.019<f ₁₃ /f ₁  (5).

Further, the distance between the first optical element and the second optical element along the optical axis is d₁, the distance between the first optical element and the first lens group along the optical axis is d₂, and d₁ and d₂ satisfy following relation (6): 0.69<d ₂ /d ₁  (6).

Further, a maximum effective optical caliber of the second optical element is φ₂, which satisfies following relation (7): φ₂<70 mm  (7).

Further, the first sub-lens group is composed of one lens; the first sub-lens group includes a first lens; and the first lens is a positive lens.

Further, the first sub-lens group is composed of two lenses, which are respectively a first lens distant from the miniature image displayer side and a second lens proximate to the miniature image displayer side; both the first lens and the second lens are positive lenses.

Further, the effective focal length of the first lens is f₁₁₁, the effective focal length of the first sub-lens group is f₁₁, and f₁₁₁ and f₁₁ satisfy following relation (8), 0.10<|f ₁₁₁ /f ₁₁|  (8).

Further, the optical surface of the first lens proximate to the human eye side is convex to the human eye.

Further, the second sub-lens group includes a third lens adjacent to the first sub-lens group; the third lens is a negative lens; the effective focal length of the third lens is f₁₂₁, and f₁₂₁ satisfies following relation (9): f ₁₂₁<−5.38  (9).

Further, the third sub-lens group includes a fourth lens adjacent to the second sub-lens group; the fourth lens is a positive lens; the effective focal length of the fourth lens is f₁₃₁, and f₁₃₁ satisfies following relation (10): 8.82<f ₁₃₁  (10).

Further, the effective focal length f₁₁ of the first sub-lens group, the effective focal length f₁₂ of the second sub-lens group, the effective focal length f₁₃ of the third sub-lens group and the effective focal length f₁ of the first lens group further satisfy following relations (11), (12), (13): 0.74<f ₁₁ /f ₁<0.81  (11); −1.03<f ₁₂ /f ₁<−0.42  (12); 0.69<f ₁₃ /f ₁<1.24  (13).

Further, the first optical element is a planar transflective optical element; a reflectivity of the first optical element is Re₁, and Re₁ satisfies relation (14): 20%<Re₁<80%  (14).

Further, a reflectivity of the optical reflection surface is Re₂, and Rea satisfies following relation (15): 20%<Re₂  (15).

Further, an angle of optical axis between the first lens group and the second optical element is λ₁, and λ₁ satisfies following relation (16): 55°<λ₁<120°  (16).

Further, the eyepiece optical system further includes a planar reflective optical element located between the first lens group and the first optical element; the planar reflective optical element reflects the image light refracted by the first lens group to the first optical element, the first optical element reflects the image light to the second optical element, and then transmits the image light reflected by the second optical element to the human eye;

the angle between the first lens group and the first optical element is λ₂, and λ₂ satisfies following relation (17): 60°≤λ₂≤180°  (17).

Further, the second optical element includes two coaxial optical surfaces of the same face shape.

Further, the first lens group includes one or more even-order aspherical face shapes; both optical surfaces of the second optical element are even-order aspherical face shapes.

Further, the even-order aspherical face shapes satisfy relational expression (18):

$\begin{matrix} {Z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {\alpha_{2}r^{2}} + {\alpha_{4}r^{4}} + {\alpha_{6}r^{6}} + {\ldots\mspace{14mu}.}}} & (18) \end{matrix}$

Further, the material of the second optical element is an optical plastic material.

The present application provides a head-mounted near-to-eye display device, including a miniature image displayer, and further including the reflective eyepiece optical system according to any one of the foregoing content; the eyepiece optical system is located between the human eye and the miniature image displayer.

Further, the miniature image displayer is an organic electroluminescent device.

Further, the head-mounted near-to-eye display device includes two identical reflective eyepiece optical systems.

The present invention has following beneficial effects: the first optical element has transmission and reflection properties, the second optical element includes a reflection surface, the eyepiece optical system composed of the first lens group, the first optical element and the second optical element is used for effectively folding the optical path, which reduces the overall size of the eyepiece optical system and improves the possibility of subsequent mass production, the first lens group includes a first sub-lens group, a second sub-lens group and a third sub-lens group, and the first sub-lens group, the second sub-lens group and the third sub-lens group adopt a combination of positive, negative and positive focal lengths. On the basis of miniaturization, cost and weight reduction for the article, the aberration of the optical system is greatly eliminated, and the basic optical indicators are also improved, ensuring high image quality and increasing the size of the picture angle. Thus an observer can watch large images of full frame, high definition and uniform image quality without any distortion and get visual experience of high liveness via the present invention, which is suitable for near-to-eye displays and similar devices thereof.

BRIEF DESCRIPTION OF DRAWINGS

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the present invention is further illustrated combining the embodiments and drawings attached. The drawings in the following description are only some embodiments of the present invention. For one of ordinary skill in the art, other drawings may be obtained from these drawings without any inventive work.

FIG. 1 is an optical path structural diagram of a reflective eyepiece optical system according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram of dispersion spots array of the reflective eyepiece optical system according to the first embodiment of the present invention;

FIG. 3a is a schematic diagram of a field curvature of the reflective eyepiece optical system according to the first embodiment of the present invention;

FIG. 3b is a schematic diagram of a distortion of the reflective eyepiece optical system according to the first embodiment of the present invention;

FIG. 4 is a plot of an optical modulation transfer function (MTF) of the reflective eyepiece optical system according to the first embodiment of the present invention;

FIG. 5 is an optical path structural diagram of a reflective eyepiece optical system according to a second embodiment of the present invention;

FIG. 6 is a schematic diagram of dispersion spots array of the reflective eyepiece optical system according to the second embodiment of the present invention;

FIG. 7a is a schematic diagram of a field curvature of the reflective eyepiece optical system according to the second embodiment of the present invention;

FIG. 7b is a schematic diagram of a distortion of the reflective eyepiece optical system according to the second embodiment of the present invention;

FIG. 8 is a plot of an optical MTF of the reflective eyepiece optical system according to the second embodiment of the present invention;

FIG. 9 is an optical path structural diagram of a reflective eyepiece optical system according to a third embodiment of the present invention;

FIG. 10 is a schematic diagram of dispersion spots array of the reflective eyepiece optical system according to the third embodiment of the present invention;

FIG. 11a is a schematic diagram of a field curvature of the reflective eyepiece optical system according to the third embodiment of the present invention;

FIG. 11b is a schematic diagram of a distortion of the reflective eyepiece optical system according to the third embodiment of the present invention;

FIG. 12 is a plot of an optical MTF of the reflective eyepiece optical system according to the third embodiment of the present invention;

FIG. 13 is an optical path structural diagram of a reflective eyepiece optical system according to a fourth embodiment of the present invention;

FIG. 14 is a schematic diagram of dispersion spots array of the reflective eyepiece optical system according to the fourth embodiment of the present invention;

FIG. 15a is a schematic diagram of a field curvature of the reflective eyepiece optical system according to the fourth embodiment of the present invention;

FIG. 15b is a schematic diagram of a distortion of the reflective eyepiece optical system according to the fourth embodiment of the present invention;

FIG. 16 is a plot of an optical MTF of the reflective eyepiece optical system according to the fourth embodiment of the present invention;

FIG. 17 is an optical path structural diagram of a reflective eyepiece optical system according to a fifth embodiment of the present invention;

FIG. 18 is a schematic diagram of dispersion spots array of the reflective eyepiece optical system according to the fifth embodiment of the present invention;

FIG. 19a is a schematic diagram of a field curvature of the reflective eyepiece optical system according to the fifth embodiment of the present invention:

FIG. 19b is a schematic diagram of a distortion of the reflective eyepiece optical system according to the fifth embodiment of the present invention;

FIG. 20 is a plot of an optical MTF of the reflective eyepiece optical system according to the fifth embodiment of the present invention:

FIG. 21a is a front view of an optical path structure of a reflective eyepiece optical system according to a sixth embodiment of the present invention;

FIG. 21b is a top view of the optical path structure of the reflective eyepiece optical system according to the sixth embodiment of the present invention;

FIG. 22 is a schematic spot diagram of the reflective eyepiece optical system according to the sixth embodiment of the present invention;

FIG. 23a is a schematic diagram of a field curvature of the reflective eyepiece optical system according to the sixth embodiment of the present invention;

FIG. 23b is a schematic diagram of a distortion of the reflective eyepiece optical system according to the sixth embodiment of the present invention; and

FIG. 24 is a plot of an optical MTF of the reflective eyepiece optical system according to the sixth embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In order to clarify the objects, technical solutions and advantages of the embodiments of the present invention, the following clear and complete description will be made for the technical solution in the embodiments of the present invention. Apparently, the described embodiments are just some rather than all embodiments of the present invention. All other embodiments obtained by one of ordinary skill in the art without any inventive work based on the embodiments disclosed in the present invention fall into the scope of the present invention.

The present invention constructs a reflective eyepiece optical system, including: a first optical element and a second optical element arranged successively along an incident direction of an optical axis of a human eye, and a first lens group located on an optical axis of a miniature image displayer; the first optical element is used for transmitting and reflecting an image light from the miniature image displayer; the second optical element includes an optical reflection surface, and the optical reflection surface is concave to an eye-viewing direction; the first optical element reflects the image light refracted by the first lens group to the second optical element, and then transmits the image light reflected by the second optical element to the human eye;

An effective focal length of the eyepiece optical system is f_(w), an effective focal length of the first lens group is f₁, an effective focal length of the second optical element is f₂, and f_(w), f₁, and f₂ satisfy following relations (1) and (2): f ₁ /f _(w)<−0.47  (1); −2.53<f ₂ /f _(w)<−0.64  (2);

wherein, a value of f₁/f_(w) may be −100.57, −56.55, −33.351, −21.131, −10.951, −7.935, −5.815, −3.615, −1.589, −0.470, etc., and a value of f₂/f_(w) may be −2.53, −2.521, −2.13, −1.99, −1.55, −1.21, −1.02, −0.98, −0.875, −0.753, −0.659, −0.64, etc.

The first lens group includes a first sub-lens group, a second sub-lens group and a third sub-lens group arranged coaxially and successively along an optical axis direction from an eye viewing side to the miniature image displayer side; the effective focal lengths of the first sub-lens group, the second sub-lens group and the third sub-lens group are a combination of positive, negative and positive; the effective focal length of the first sub-lens group is f₁₁, the effective focal length of the second sub-lens group is f₁₂, the effective focal length of the third sub-lens group is f₁₃, and f₁₁, f₁₂, f₁₃ and f₁ satisfy following relations (3), (4) and (5): 0.19<f ₁₁ /f ₁  (3); f ₁₂ /f ₁<−0.019  (4); 0.019<f ₁₃ /f ₁  (5);

wherein, a value of f₁₁/f₁ may be 0.19, 0.20, 0.39, 0.57, 0.77, 0.89, 1.35, 3.25, 5.56, 36.1, 54.1, 87.6, etc., a value of f₁₂/f₁ may be −120.43, −100.47, −77.55, −51.25, −45.33, −21.78, −15.13, −10.55, −7.15, −4.14, −0.13, −0.02, −0.019, etc., and a value of f₁₃/f₁ may be 0.019, 0.139, 1.99, 5.83, 12.13, 22.54, 35.24, 43.55, 83.59, etc.

In the above relations (1), (2), (3), (4) and (5), the value ranges of f₁/f_(w), f₂/f_(w), f₁₁/f₁, f₁₂/f₁ and f₁₃/f₁ are closely related to sensitivities of a correction of system aberrations, a processing difficulty of optical members, and assembly deviations of the optical elements, wherein the value of f₁/f_(w) in relation (1) is less than −0.47, which improves the processibility of the optical elements in the system; the value of f₂/f_(w) in relation (2) is greater than 0.2.53, which improves the processibility of the optical elements in the system, while its value is less than −0.64, so that the system aberration can be fully corrected, so as to achieve higher quality optical effects. The value of f₁₁/f₁ in relation (3) is greater than 0.19, so that the system aberration can be fully corrected, so as to achieve quality optical effects; the value of f₁₂/f₁ in relation (5) is larger than 0.019, so that the system aberration can be fully corrected, so as to achieve quality optical effects. The value of f₁₂/f₁ in relation (4) is less than −0.019, which reduces difficulty of spherical aberration correction and facilitates realization of a large optical aperture.

The first lens group includes three sub-lens groups, which are respectively a first sub-lens group, a second sub-lens group and a third sub-lens group arranged adjacently, the first sub-lens group, the second sub-lens group and the third sub-lens group adopt a combination of positive, negative and positive focal lengths. The negative lens group corrects aberrations and the positive lens group provides focused imaging. The combination of respective sub-lens group is relatively complex, which can better correct aberrations, has better processability, fully corrects the aberrations of the system, and improves the optical resolution of the system.

More importantly, with the transmission and reflection properties of the first optical element, the second optical element has a reflective surface to effectively fold the optical path, which reduces the overall size of the eyepiece optical system, and improves the possibility of subsequent mass production. On the basis of miniaturization, cost and weight reduction for the article, the aberration of the optical system is greatly eliminated, and the basic optical indicators are also improved to ensure high imaging quality and increase the size of the picture angle. Thus an observer can watch large images of full frame, high definition and uniform image quality without any distortion and get visual experience of high liveness via the present invention, and the present article is suitable for head-mounted near-to-eye display devices and similar devices.

In the above embodiment, the first optical element may be a polarizer with 75% transmission, 25% reflection or 65% transmission, 35% reflection or a transflective function. The second optical element is a component only with a reflective function, which may be a lens or a metal piece with a reflective function.

As shown in FIG. 1, a first optical element, a second optical element, and a first lens group arranged along an optical axis direction between an eye viewing side and a miniature image displayer are included. The optical surface closer to the eye E side is marked as 1, and by analogy (2, 3, 4, 5, 6 . . . respectively from left to right). The light emitted from the miniature image displayer is refracted by the first lens group, and then reflected on the first optical element to the second optical element, and the light is reflected by the second optical element s onto the first optical element, and then transmits to the human eye through the first optical element.

In a further embodiment, the distance between the first optical element and the second optical element along the optical axis is d₁, the distance between the first optical element and the first lens group along the optical axis is d₂, and d₁ and d₂ satisfy following relation (6): 0.69<d ₂ /d ₁  (6);

wherein, a value of d₂/d₁ may be 0.69, 0.695, 0.88, 0.98, 1.55, 2.37, 3.55, 3.88, 3.99, 4.57, 4.89, 4.99, etc.

The lower limit of d₂/d₁ in the above relation (6) is greater than 0.69, which reduces difficulty of correcting an off-axis aberration of the system, and ensures that both a central field-of-view and an edge field-of-view achieve high image quality, so that the image quality in the full frame is uniform.

In a further embodiment, a maximum effective optical caliber of the second optical element is φ₂, which satisfies following relation (7): φ₂<70 mm  (7);

wherein, a value of 972 may be 70, 65, 56, 52, 48, 32, 30, 28, 26, 21, etc., in mm.

In one of the embodiments, the first sub-lens group is composed of one lens; the first sub-lens group includes a first lens; and the first lens is a positive lens.

In one of the embodiments, the first sub-lens group is composed of two lenses, respectively a first lens distant from the miniature image displayer side and a second lens proximate to the miniature image displayer side; both the first lens and the second lens are positive lenses.

In a further embodiment, the effective focal length of the first lens is f₁₁₁, and the effective focal length of the first sub-lens group is f₁₁, f₁₁₁ and f₁₁ satisfy following relation (8): 0.10<|f ₁₁₁ /f ₁₁|  (8);

wherein, a value of |f₁₁₁/f₁₁| may be 0.10, 0.11, 0.22, 0.58, 1.32, 1.55, 2.25, 3.57, 5.57, 8.79, 9.91, 10.11, 20.22, etc.

The value of |f₁₁₁/f₁₁| in relation (8) is greater than 0.10, so that the system aberration can be fully corrected, so as to achieve high-quality optical effects.

In a further embodiment, the optical surface of the first lens proximate to the human eye side is convex to the human eye. It may further reduce the size of the eyepiece optical system, improve the image quality of the system, correct the distortion, and improve the aberrations such as astigmatism and field curvature of the system, which is beneficial to the high-resolution optical effect of the eyepiece system with uniform image quality across the full frame.

In a further embodiment, the second sub-lens group includes a third lens; the third lens is a negative lens; the effective focal length of the third lens is f₁₂₁, and f₁₂₁ satisfies following relation (9): f ₁₂₁<−5.38  (9);

wherein, a value of f₁₂₁ may be −5.38, −5.39, −6.72, −9.88, −21.32, −41.55, −52.25, −63.57, −75.57, −88.79, −99.91, −110.11, −220.22, etc.

In the relation (9), the value of f₁₂₁ is less than −5.38, which reduces difficulty of spherical aberration correction and facilitates realization of a large optical aperture.

In a further embodiment, the third sub-lens group includes a fourth lens; the fourth lens is a positive lens; the effective focal length of the fourth lens is f₃₁, and f₁₃₁ satisfies following relation (10): 8.82<f ₁₃₁  (10);

wherein, a value of f₁₃₁ may be 8.82, 8.83, 9.72, 19.88, 21.32, 41.55, 52.25, 63.57, 75.57, 88.79, 99.91, 110.11, 220.22, etc.

The value of f₁₃₁ in the relation (10) is greater than 8.82, so that the system aberration can be fully corrected, so as to achieve high-quality optical effects.

In a further embodiment, the effective focal length f₁₁ of the first sub-lens group, the effective focal length f₁₂ of the second sub-lens group, the effective focal length f₁₃ of the third sub-lens group, and the effective focal length f₁ of the first lens group, further satisfy following relations (11), (12) and (13): 0.74<f ₁₁ /f ₁<0.81  (11); −1.03<f ₁₂ /f ₁<−0.42  (12); 0.69<f ₁₃ /f ₁<1.24  (13);

wherein, a value of f₁₁/f₁ may be 0.74, 0.75, 0.759, 0.761, 0.775, 0.789, 0.795, 0.80, 0.802, 0.805, 0.809, 0.81, etc., a value of f₁₂/f₁ may be −1.03, −1.02, −0.928, −0.81, −0.706, −0.695, −0.575, −0.535, −0.47, −0.43, −0.42, etc., and a value of f₁₃/f₁ may be 0.69, 0.70, 0.723, 0.790, 0.815, 0.898, 1.07, 1.11, 1.21, 1.23, 1.24, etc.

By further optimizing the value ranges of the effective focal length of the first sub-lens group, the second sub-lens group, the third sub-lens group and the system, the optical performance and difficulty of processing and manufacturing of the optical system are better balanced.

In a further embodiment, the first optical element is a planar transflective optical element; a reflectivity of the first optical element is Re₁, and Re₁ satisfies relation (14): 20%<Re₁<80%  (14):

wherein, a value of Re₁ may be 20%, 21%, 30%, 47%, 52%, 60%, 65%, 70%, 79%, 80%, etc.

In a further embodiment, a reflectivity of the optical reflection surface is Re₂, and Re₂ satisfies following relation (15): 20%<Re₂  (15);

wherein, a value of Re₂ may be 20%, 21%, 30%, 47%, 52%, 60%, 65%, 70%, 80%, 99%, etc.

In a further embodiment, an angle of optical axis between the first lens group and the second optical element is λ₁, and λ₁ satisfies the following relation (16): 55°<λ₁<120°  (16);

wherein, a value of λ₁ may be 55°, 60°, 66°, 70°, 90°, 100°, 115°, 120°, etc.

In one of the embodiments, the eyepiece optical system further includes a planar reflective optical element located between the first lens group and the first optical element; the planar reflective optical element reflects the image light refracted by the first lens group to the first optical element, the first optical element reflects the image light to the second optical element, and then transmits the image light reflected by the second optical element to the human eye;

The angle between the first lens group and the first optical element is λ₂, and λ₂ satisfies following relation (17): 60°≤λ₂≤180°  (17);

wherein, a value of λ₂ may be 60°, 74°, 80°, 90°, 100°, 130°, 140°, 55°. 167°, 180°, etc.

In a further embodiment, the second optical element includes two coaxial optical surfaces of the same face shape.

In a further embodiment, the first lens group includes one or more even-order aspherical face shapes; both optical surfaces of the second optical element are even-order aspherical face shapes.

The aberrations at all levels of the optical system are further optimized and corrected. The optical performance of the eyepiece optical system is further improved.

In a further embodiment, the even-order aspherical face shapes satisfy relation (18):

$\begin{matrix} {Z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {\alpha_{2}r^{2}} + {\alpha_{4}r^{4}} + {\alpha_{6}r^{6}} + {\ldots\mspace{14mu}.}}} & (18) \end{matrix}$

wherein, Z is a vector height of the optical surface, c is a curvature at the aspherical vertex, k is an aspherical coefficient, and α2,4,6 . . . are coefficients of various orders, and r is a distance coordinate from a point on a surface to an optical axis of a lens system.

The aberrations of the optical system (including spherical aberration, coma, distortion, field curvature, astigmatism, chromatic aberration and other higher-order aberrations) are fully corrected, which is beneficial for the eyepiece optical system, while realizing a large angle of view and a large aperture, to further improve the image quality of the central field-of-view and the edge field-of-view reduce the image quality difference between the central field-of-view and the edge field-of-view, achieving more uniform image quality and low distortion in the full frame.

In a further embodiment, the material of the second optical element is an optical plastic material, such as E48R, EP5000, OKP1, etc.

The aberrations at all levels of the eyepiece optical system are fully corrected, and the manufacturing cost of the optical element and the weight of the optical system are also controlled.

The principles, solutions and display results of the above-mentioned eyepiece optical system will be further described below through more specific examples.

In the following examples, the diaphragm E may be the exit pupil of imaging for the eyepiece optical system, which is a virtual light exit aperture. When the pupil of the human eye is at the diaphragm position, the best imaging effect can be observed.

Example 1

The eyepiece design data of Example 1 is shown in Table 1 below:

TABLE 1 Lens Net Curvature Thickness Refractive Abbe caliber Cone Surface radius (mm) (mm) index number (mm) coefficient Diaphragm Infinite 47 4 2 −37.92548 −20 reflection 40.15334 −9.139336 3 Infinite 22.7896 reflection 16.69056 4 28.37282 9.02467 1.8537 40.598749 12 −16.58263 5 −20.45578 0.1994643 16.14019 −0.7006549 6 −23.97738 3.466431 1.945958 17.943914 15.46808 −2.114405 7 44.87586 1.549316 15.60756 7.569478 8 20.86865 5.254431 1.833996 37.229136 15.6 −4.439424 9 63.49841 17.11 17.1124 41.54056 Image Infinite 21.44313 plane

FIG. 1 is an optical path diagram of the eyepiece optical system of Example 1, including: a first optical element L1 and a second optical element T2 arranged successively along the incident direction of the optical axis of the human eye, and a first lens group T1 located on the optical axis of the miniature image displayer IMG; the first optical element L1 is used for transmitting and reflecting the image light from the miniature image displayer IMG; the second optical element 12 includes an optical reflection surface L2, and the optical reflection surface L2 is concave to the eye-viewing direction; the first optical element L1 reflects the image light refracted by the first lens group T1 to the second optical element T2, and then transmits the image light reflected by the second optical element T2 to the human eye EYE.

The effective focal length f_(w) of the eyepiece optical system is −28.21, the effective focal length f₁ of the first lens group T1 is 13.54, the effective focal length f₂ of the second optical element T2 is 20.56, the distance d₁ between the first optical element L1 and the second optical element T2 along the optical axis is 20, the distance d₂ between the first optical element L1 and the first lens group T1 along the optical axis is 22.79, wherein the first lens group T1 includes a first sub-lens group T11, a second sub-lens group T12 and a third sub-lens group T13, the first sub-lens group T11 is composed of a positive lens, which is the first lens T111, the effective focal length f₁ of the first sub-lens group T11 is 10.11; the second sub-lens group T12 is composed of a negative lens, which is the third lens T121, the effective focal length f₁₂ of the second sub-lens group T12 is −11.21; the third sub-lens group is composed of a positive lens, which is the fourth lens T131, the effective focal length f₁₃ of the third sub-lens group T13 is 15.26. And f₁/f_(w) is −0.48, f₂/f_(w) is −0.73, f₁₁/f₁ is 0.75, f₁₁₁/f₁₁ is 1, f₁₂/f₁ is −0.83, f₁₃/f₁ is 1.13, f₁₂₁ is −11.21, f₁₃₁ is 15.26, d₂/d₁ is 1.14, and λ₁ is 72°.

FIGS. 2, 3 a, 3 b and 4 are respectively a dispersion spots array diagram, a field curvature, a distortion diagram and a transfer function MTF plot, which reflect that respective field-of-view light in this example has high resolution and small optical distortion in the unit pixel of the image plane (miniature image displayer IMG), the resolution per 10 mm per unit period reaches more than 0.9, the aberration of the optical system and the image drift are well corrected, and a display image of uniformity and high optical performance can be observed through the eyepiece optical system.

Example 2

The eyepiece design data of Example 2 is shown in Table 2 below:

TABLE 2 Lens Net Curvature Thickness Refractive Abbe caliber Cone Surface radius (mm) (mm) index number (mm) coefficient Diaphragm Infinite 37 5 2 −30.9247 −17 reflection 31.08349 −4.748349 3 Infinite 23.4579 reflection 18.33266 4 27.87133 6.827359 1.7433 49.238028 8.100567 −15.62273 5 −7.951117 0.1990611 5.552825 −7.803999 6 −10.36753 1.863405 1.71736 29.509994 5.206458 −17.3051 7 19.15627 0.355614 4.939304 21.89432 8 26.537 4.995075 1.7725 49.613485 5.174862 50.00145 9 −10.91228 19.22921 6.94284 Image Infinite 14.59879 plane

FIG. 5 is an optical path diagram of the eyepiece optical system of the Example 2, including: a first optical element L1 and a second optical element T2 arranged successively along the incident direction of the optical axis of the human eye, and a first lens group T1 located on the optical axis of the miniature image displayer IMG; the first optical element L1 is used for transmitting and reflecting the image light from the miniature image displayer IMG; the second optical element T2 includes an optical reflection surface L2, and the optical reflection surface L2 is concave to the eye-viewing direction; the first optical element L1 reflects the image light refracted by the first lens group T1 to the second optical element T2, and then transmits the image light reflected by the second optical element T2 to the human eye EYE.

The effective focal length f_(w) of the eyepiece optical system is −18.97, the effective focal length f₁ of the first lens group T1 is 12.59, the effective focal length f_(z) of the second optical element T2 is 12.33, the distance d₁ between the first optical element L1 and the second optical element T2 along the optical axis is 17, the distance d₂ between the first optical element L1 and the first lens group T1 along the optical axis is 23.46, wherein the first lens group T1 includes a first sub-lens group T11, a second sub-lens group T12 and a third sub-lens group T13, the first sub-lens group T11 is composed of a positive lens, which is the first lens T111, and the effective focal length f₁ of the first sub-lens group T11 is 7.68; the second sub-lens group T12 is composed of a negative lens, which is the third lens T121, and the effective focal length f₁₂ of the second sub-lens group T12 is −5.39; the third sub-lens group is composed of a positive lens, which is the fourth lens T131, and the effective focal length f₁₃ of the third sub-lens group T13 is 8.83. And f₁/f_(w) is −0.66, f₂/f_(w) is −0.65, f₁₁/f₁ is 0.61, f₁₁₁/f₁₁ is 1, f₁₂/f₁ is −0.43, f₁₃/f₁ is −0.7, f₁₂₁ is −5.39, f₁₃₁ is 8.83, d₂/d₁ is 1.38, and λ₁ is 70°.

FIGS. 6, 7 a, 7 b and 8 are respectively a dispersion spots array diagram, a field curvature, a distortion diagram and a transfer function MTF plot, which reflect that respective field-of-view light in this example has high resolution and small optical distortion in the unit pixel of the image plane (miniature image displayer IMG), the resolution per 10 mm per unit period reaches more than 0.9, the aberration of the optical system and the image drift are well corrected, and a display image of uniformity and high optical performance can be observed through the eyepiece optical system.

Example 3

The eyepiece design data of Example 3 is shown in Table 3 below:

TABLE 3 Lens Net Curvature Thickness Refractive Abbe caliber Cone Surface radius (mm) (mm) index number (mm) coefficient Diaphragm Infinite 35 5 2 −38.47191 −13.8007 reflection 29.14309 1.653179 3 Infinite 20.41 reflection 35.45597 4 9.132185 5.88968 1.804005 46.59095 9.734725 −1.831343 5 −28.94736 0.4776587 11.06175 −0.482368 6 −9.41989 1.49817 1.66059 20.401227 10.91348 7 26.26909 0.9086105 12.3568 8 39.11695 3.463132 1.802793 46.774142 13.14257 9 −12.82956 12.96857 13.50391 Image Infinite 8.733005 plane

FIG. 9 is an optical path diagram of the eyepiece optical system of Example 3, including: a first optical element L1 and a second optical element T2 arranged successively along the incident direction of the optical axis of the human eye, and a first lens group T1 located on the optical axis of the miniature image displayer IMG; the first optical element L1 is used for transmitting and reflecting the image light from the miniature image displayer IMG; the second optical element T2 includes an optical reflection surface L2, and the optical reflection surface 12 is concave to the eye-viewing direction; the first optical element L1 reflects the image light refracted by the first lens group T1 to the second optical element T2, and then transmits the image light reflected by the second optical element T2 to the human eye EYE.

The effective focal length f_(w) of the eyepiece optical system is −11.21, the effective focal length f₁ of the first lens group T1 is 10.11, the effective focal length f₂ of the second optical element T2 is 15.32, the distance d₁ between the first optical element L1 and the second optical element T2 along the optical axis is 16.59, the distance d₂ between the first optical element L1 and the first lens group T1 along the optical axis is 11.62, wherein the first lens group T1 includes a first sub-lens group T11, a second sub-lens group T12 and a third sub-lens group T13, the first sub-lens group T11 is composed of a positive lens, which is the first lens T111, and the effective focal length f₁₁ of the first sub-lens group T11 is 8.09; the second sub-lens group T12 is composed of a negative lens, which is the third lens T121, and the effective focal length f₁₂ of the second sub-lens group T12 is −10.32; the third sub-lens group is composed of a positive lens, which is the fourth lens T131, and the effective focal length f₁₃ of the third sub-lens group T13 is 12.4, and f₁/f_(w) is −0.9, f₂/f_(w) is −1.37, f₁₁/f₁ is 0.8, f₁₁₁/f₁₁ is 1, f₁₂/f₁ is −1.02, f₁₃/f₁ is 1.23, f₁₂₁ is −10.32, d₂/d₁ is 0.7, and λ₁ is 70°.

FIGS. 10, 11 a, 11 b and 12 are respectively a dispersion spots diagram, a field curvature, a distortion diagram and a transfer function MTF plot, which reflect that respective field-of-view light in this example has high resolution and small optical distortion in the unit pixel of the image plane (miniature image displayer IMG), the resolution per 10 mm per unit period reaches more than 0.9, the aberration of the optical system and the image drift are well corrected, and a display image of uniformity and high optical performance can be observed through the eyepiece optical system.

Example 4

The eyepiece design data of Example 4 is shown in Table 4 below:

TABLE 4 Lens Net Curvature Thickness Refractive Abbe caliber Cone Surface radius (mm) (mm) index number (mm) coefficient Diaphragm Infinite 25 4 2 −49.36142 −13.5 reflection 16.92878 −30.63446 3 Infinite 13.1334 reflection 16.47546 4 10.63173 6.768553 1.470466 66.884514 11.45823 1.642487 5 3.274199 11.32313 6.427964 −0.03205 6 7.530389 3.420425 1.6516 58.416296 6.330415 −2.823889 7 −13.30309 0.01089893 6.564714 −2.0235 8 −6.043257 1.444582 1.66059 20.401227 6.441418 9 −26.53271 0.5485741 6.698429 10 50.10796 2.513006 1.533232 56.175258 6.721603 11 −8.1199 7.032609 6.67126 Image 4.694998 plane

FIG. 13 is an optical path diagram of the eyepiece optical system of Example 4, including: a first optical element L1 and a second optical element T2 arranged successively along the incident direction of the optical axis of the human eye, and a first lens group T1 located on the optical axis of the miniature image displayer IMG; the first optical element L is used for transmitting and reflecting the image light from the miniature image displayer IMG; the second optical element T2 includes an optical reflection surface L2, and the optical reflection surface 12 is concave to the eye-viewing direction; the first optical element L1 reflects the image light refracted by the first lens group T1 to the second optical element T2, and then transmits the image light reflected by the second optical element T2 to the human eye EYE.

The effective focal length f_(w) of the eyepiece optical system is −7.8, the effective focal length f₁ of the first lens group T1 is 782.9, the effective focal length f₂ of the second optical element T2 is 19.69, the distance d₁ between the first optical element L1 and the second optical element T2 along the optical axis is 12.8, the distance d₂ between the first optical element L1 and the first lens group T1 along the optical axis is 13.83, wherein the first lens group T1 includes a first sub-lens group T11, a second sub-lens group T12 and a third sub-lens group T13, the first sub-lens group T11 is composed of two positive lenses, which are respectively the first lens T111 distant from the miniature image displayer side and the second lens T112 proximate to the miniature image displayer side; the effective focal length f₁₁ of the first sub-lens group T11 is 154.93, the effective focal length f₁₁₁ of the first lens T111 is 17.29; the second sub-lens group T12 is composed of a negative lens, the lens is the third lens T121, and the effective focal length f₁₂ of the second sub-lens group T12 is −12.19; the third sub-lens group is composed of a positive lens, the lens is the fourth lens T131, and the effective focal length f₁₃ of the third sub-lens group T13 is 13.3. And f₁/f_(w) is −100.37, f₂/f_(w) is −2.52, f₁₁/f₁ is 0.2, f₁₁₁/f₁₁ is 0.11, f₁₂/f₁ is −0.02, f₁₃/f₁ is 0.02, f₁₂₁ is −14.98, d₂/d₁ is 0.70, and λ₁ is 56°.

FIGS. 14, 15 a, 15 b and 16 are respectively a dispersion spots array diagram, a field curvature, a distortion diagram and a transfer function MTF plot, which reflect that respective field-of-view light in this example has high resolution and small optical distortion in the unit pixel of the image plane (miniature image displayer IMG), the resolution per 10 mm per unit period reaches more than 0.9, the aberration of the optical system and the image drift are well corrected, and a display image of uniformity and high optical performance can be observed through the eyepiece optical system.

Example 5

The eyepiece design data of Example 5 is shown in Table 5 below:

TABLE 5 Lens Net Curvature Thickness Refractive Abbe caliber Cone Surface radius (mm) (mm) index number (mm) coefficient Diaphragm Infinite 35 4 2 −46.67614 −15.8007 reflection 33.1748 3.085973 3 Infinite 17.5918 reflection 39.82343 4 52.49173 3.132752 1.746934 51.008591 9.556477 24.59786 5 13.01616 0.9286545 7.78054 6.399797 6 22.46667 6.510699 1.6968 55.534184 7.621695 −19.00484 7 −29.99283 0.4835252 5.64488 20.72191 8 11.6405 3.384979 1.672707 32.180986 4.395748 9 10.21003 4.078799 4.380214 10 9.653885 5.22739 1.613095 60.614383 9.892366 11 −119.9915 5.717896 10.41139 Image Infinite 11.53956 plane

FIG. 17 is an optical path diagram of the eyepiece optical system of Example 5, including: a first optical element L1 and a second optical element T2 arranged successively along the incident direction of the optical axis of the human eye, and a first lens group T1 located on the optical axis of the miniature image displayer IMG; the first optical element L1 is used for transmitting and reflecting the image light from the miniature image displayer IMG; the second optical element T2 includes an optical reflection surface L2, and the optical reflection surface L2 is concave to the eye-viewing direction; the first optical element L1 reflects the image light refracted by the first lens group T1 to the second optical element T2, and then transmits the image light reflected by the second optical element T2 to the human eye EYE.

The effective focal length f_(w) of the eyepiece optical system is −13.5, the effective focal length f₁ of the first lens group T1 is 10.89, and the effective focal length f₂ of the second optical element T2 is 18.6, the distance d₁ between the first optical element L1 and the second optical element T2 along the optical axis is 12.8, and the distance d₂ between the first optical element L1 and the first lens group T1 along the optical axis is 20.57. The first lens group T1 includes a first sub-lens group T11, a second sub-lens group T12 and a third sub-lens group T13, the first sub-lens group T11 is composed of two positive lenses, which are respectively the first lens T111 distant from the miniature image displayer side and the second lens T112 proximate to the miniature image displayer side; the effective focal length f₁₁ of the first sub-lens group T11 is 13.1, the effective focal length f₁₁₁ of the first lens T11(T111) is 22.56; the second sub-lens group T12 is composed of a negative lens, which is the third lens T121, and the effective focal length f₁₂ of the second sub-lens group T12 is −2555.29; the third sub-lens group is composed of a positive lens, which is the fourth lens T131, and the effective focal length f₁₃ of the third sub-lens group T13 is 14.8, And f₁/f_(w) is −0.81, f₂/f_(w) is −1.38, f₁₁/f₁ is 1.2, f₁₁₁/f₁₁ is 1.72, f₁₂/f₁ is −234.65, f₁₃/f₁ is 1.36, f₂₁ is −2555.29, d₂/d₁ is 1.61, and λ₁ is 70°.

FIGS. 18, 19 a, 19 b and 20 are respectively a dispersion spots array diagram, a field curvature, a distortion diagram and a transfer function MTF plot, which reflect that respective field-of-view light in this example has high resolution and small optical distortion in the unit pixel of the image plane (miniature image displayer IMG), the resolution per 10 mm per unit period reaches more than 0.9, the aberration of the optical system and the image drift are well corrected, and a display image of uniformity and high optical performance can be observed through the eyepiece optical system.

Example 6

The eyepiece design data of Example 6 is shown in Table 6 below:

TABLE 6 Lens Net Curvature Thickness Refractive Abbe caliber Cone Surface radius (mm) (mm) index number (mm) coefficient Diaphragm Infinite 47 5 2 −54.43931 −24 reflection 48.95158 −14.05856 3 Infinite 32.3114 reflection 59.65487 4 Infinite −10 reflection 13.32531 5 −16.44166 −2.618275 1.53116 56.043828 7.833633 −1.749706 6 −32.72957 −2.152342 7.364828 −34.94002 7 −16.67698 −6.506248 1.651133 55.903805 8.317541 −2.015585 8 15.67356 −0.2656935 8.599111 0.8499103 9 20.37391 −3.964838 1.64219 22.408848 8.492684 −3.615109 10 −29.40104 −2.29513 9.577369 −16.08668 11 −142.7324 −4.385973 1.72 50.351963 10.89104 −4.662146 12 61.45032 −6.68695 12.29765 9.621991 13 −17.92474 −5 1.80999 41.000073 16.57147 −6.966687 14 −19.54462 −6.85811 15.97538 −0.1664377 Image Infinite 17.60037 plane

FIGS. 21a and 21b are a front view and a top view of the optical path of the eyepiece optical system of Example 6, including a first lens group T1, and a first optical element L1 and a second optical element T2 for transmitting and reflecting light from the miniature image displayer IMG, and further including a planar reflective optical element L3 located between the first lens group and the first optical element; the second optical element T2 includes an optical reflection surface S2, and the optical reflection surface S2 is the optical surface farthest from the eye viewing side in the second optical element T2; the optical reflection surface S2 is concave to the eye-viewing direction; the planar reflective optical element L3 reflects the light refracted by the first lens group T1 to the first optical element L1, the first optical element L1 reflects the light onto the second optical element T2, and then transmits the light reflected by the second optical element T2 to the human eye EYE.

The first lens group T1 includes a first sub-lens group T11, a second sub-lens group T12 and a third sub-lens group T13, the first sub-lens group T11 is a positive lens group, the second sub-lens group T12 is a negative lens group, and the third sub-lens group T13 is a positive lens group. The first sub-lens group T11 is composed of a first lens T111 and a second lens T112, and both the first lens T11 and the second lens T12 are positive lenses. The second sub-lens group T12 is composed of a third lens T121, and the third lens T121 is a negative lens. The third sub-lens group T13 is composed of a fourth lens T131, and the fourth lens T131 is a positive lens.

The effective focal length f_(w) of the eyepiece optical system is −16.7, the effective focal length f of the first lens group T1 is 16.76, and the effective focal length f₂ of the second optical element T2 is 27.22, the distance d₁ between the first optical element L1 and the second optical element T2 along the optical axis is 24, the distance d₂ between the first optical element L1 and the first lens group T1 along the optical axis is 42.31, wherein, d₂ consists of d₂₁ and d₂₂. The effective focal length f₁₁ of the first sub-lens group T11 is 12.26, the effective focal length f₁₁₁ of the first lens T111 is 58.91, the effective focal length f₁₂ of the second sub-lens group T12 is −18.17, and the effective focal length f₁₃ of the third sub-lens group T13 is 60.2. And f₁/f_(w) is −1.0, f₂/f_(w) is −1.63, f₁₁/f₁ is 0.73, f₁₁₁/f₁₁ is 4.81, f₁₂/f₁ is −1.08, f₁₃/f₁ is 3.59, the effective focal length f₁₂₁ of the third lens T121 is −18.17, d₂/d₁ is 1.76, λ₁ is 74°, and λ₂ is 90′.

FIGS. 22, 23 a, 23 b and 24 are respectively a spot diagram, a field curvature, a distortion diagram and a transfer function MTF plot, which reflect that respective field-of-view light in this example has high resolution and small optical distortion in the unit pixel of the image plane (miniature image displayer IMG), the resolution per 10 mm per unit period reaches more than 0.9, the aberration of the optical system and the image drift are well corrected, and a display image of uniformity and high optical performance can be observed through the eyepiece optical system.

The data of the above-mentioned Examples 1 to 6 all meet the parameter requirements recorded in the Summary of the present invention, and the results are shown in the following Table 7:

TABLE 7 f₁/f_(w) f₂/f_(w) f₁₁/f₁ f₁₁₁/f₁₁ f₁₂/f₁ f₁₃/f₁ Example 1 −0.48 −0.73 0.75 1 −0.83 1.13 Example 2 −0.66 −0.65 0.61 1 −0.43 0.7 Example 3 −0.9 −1.37 0.8 1 −1.02 1.23 Example 4 −100.37 −2.52 0.2 0.11 −0.02 0.02 Example 5 −0.81 −1.38 1.2 1.72 −234.65 1.36 Example 6 −1.0 −1.63 0.73 4.81 −1.08 3.59

The present application provides a head-mounted near-to-eye display device, including a miniature image displayer, and further including the reflective eyepiece optical system according to any one of the foregoing content; the eyepiece optical system is located between the human eye and the miniature image displayer.

Preferably, the miniature image display is an organic electroluminescent device.

Preferably, the head-mounted near-to-eye display device includes two identical reflective eyepiece optical systems.

To sum up, the first lens group of the reflective eyepiece optical system in the above examples of the present invention includes two sub-lens groups, which are the first sub-lens group, the second sub-lens group and the third sub-lens group, respectively, the effective focal lengths of the first sub-lens group, the second sub-lens group and the third sub-lens group adopt a combination of positive, negative and positive, which fully corrects the aberration of the system and improves the optical resolution of the system. More importantly, with the transmission and reflection properties of the first optical element, the second optical element has a reflection surface, which effectively folds the optical path, reduces the overall size of the eyepiece optical system, and improves the possibility of subsequent mass production. On the basis of miniaturization, cost and weight reduction for the article, the aberration of the optical system is greatly eliminated, and the basic optical indicators are also improved, ensuring high image quality and increasing the size of the picture angle. Thus an observer can watch large images of full frame, high definition and uniform image quality without any distortion and get visual experience of high liveness via the present invention, and the present article is suitable for head-mounted near-to-eye display devices and similar devices.

It should be understood that, for one of ordinary skill in the art, the foregoing description can be modified or altered, and all such modifications and alterations fall into the scope of the attached claims of the present invention. 

What is claimed is:
 1. A reflective eyepiece optical system, comprising: a first optical element and a second optical element arranged successively along an incident direction of an optical axis of a human eye, and a first lens group located on an optical axis of a miniature image displayer; wherein the first optical element is used for transmitting and reflecting an image light from the miniature image displayer; the second optical element comprises an optical reflection surface, and the optical reflection surface is concave to the human eye; the first optical element reflects the image light refracted by the first lens group to the second optical element, and then transmits the image light reflected by the second optical element to the human eye; an effective focal length of the eyepiece optical system is f_(w), an effective focal length of the first lens group is f₁, an effective focal length of the second optical element is f₂, and f_(w), f₁, f₂ satisfy the following relations (1), (2): f ₁ /f _(w)<−0.47  (1); −2.53<f ₂ /f _(w)<−0.64  (2); the first lens group comprises a first sub-lens group, a second sub-lens group and a third sub-lens group arranged coaxially and successively along the optical axis direction from a human eye viewing side to the miniature image displayer side; the effective focal lengths of the first sub-lens group, the second sub-lens group and the third sub-lens group are a combination of positive, negative and positive; the effective focal length of the first sub-lens group is f₁₁, the effective focal length of the second sub-lens group is f₁₂, the effective focal length of the third sub-lens group is f₁₃, and f₁₁, f₁₂, f₁₃ and f₁ satisfy the following relations (3), (4), (5): 0.19<f ₁₁ /f ₁  (3); f ₁₂ /f ₁<−0.019  (4); 0.019<f ₁₃ /f ₁  (5).
 2. The reflective eyepiece optical system according to claim 1, wherein the distance between the first optical element and the second optical element along the optical axis is d₁, the distance between the first optical element and the first lens group along the optical axis is d₂, and d₁ and d₂ satisfy following relation (6): 0.69<d ₂ /d ₁  (6).
 3. The reflective eyepiece optical system according to claim 1, wherein a maximum effective optical caliber of the second optical element is φ₂, which satisfies following relation (7): φ₂<70 mm  (7).
 4. The reflective eyepiece optical system according to claim 1, wherein the first sub-lens group is composed of one lens; the first sub-lens group comprises a first lens; and the first lens is a positive lens.
 5. The reflective eyepiece optical system according to claim 1, wherein the first sub-lens group is composed of two lenses, which are respectively a first lens distant from the miniature image displayer side and a second lens proximate to the miniature image displayer side; both the first lens and the second lens are positive lenses.
 6. The reflective eyepiece optical system according to claim 4, wherein the effective focal length of the first lens is f₁₁₁, the effective focal length of the first sub-lens group is f₁₁, and f₁₁₁ and f₁₁ satisfy following relation (8), 0.10<|f ₁₁₁ /f ₁₁|  (8).
 7. The reflective eyepiece optical system according to claim 4, wherein the optical surface of the first lens proximate to the human eye side is convex to the human eye.
 8. The reflective eyepiece optical system according to claim 1, wherein the second sub-lens group comprises a third lens adjacent to the first sub-lens group; the third lens is a negative lens; the effective focal length of the third lens is f₁₂₁, and f₁₂₁ satisfies following relation (9): f ₁₂₁<−5.38  (9).
 9. The reflective eyepiece optical system according to claim 1, wherein the third sub-lens group comprises a fourth lens adjacent to the second sub-lens group; the fourth lens is a positive lens; the effective focal length of the fourth lens is f₁₃₁, and f₁₃₁ satisfies following relation (10): 8.82<f ₁₃₁  (10).
 10. The reflective eyepiece optical system according to claim 1, wherein the effective focal length f₁₁ of the first sub-lens group, the effective focal length f₁₂ of the second sub-lens group, the effective focal length f₁₃ of the third sub-lens group and the effective focal length f₁ of the first lens group further satisfy following relations (11), (12), (13): 0.74<f ₁₁ /f ₁<0.81  (11); −1.03<f ₁₂ /f ₁<−0.42  (12); 0.69<f ₁₃ /f ₁<1.24  (13).
 11. The reflective eyepiece optical system according to claim 1, wherein the first optical element is a planar transflective optical element; a reflectivity of the first optical element is Re₁, and Re₁ satisfies relation (14): 20%<Re₁<80%  (14).
 12. The reflective eyepiece optical system according to claim 1, wherein a reflectivity of the optical reflection surface is Re₂, and Re₂ satisfies following relation (15): 20%<Re₂  (15).
 13. The reflective eyepiece optical system according to claim 1, wherein an angle of optical axis between the first lens group and the second optical element is λ₁, and λ₁ satisfies following relation (16): 55°<λ₁<120°  (16).
 14. The reflective eyepiece optical system according to claim 1, wherein the eyepiece optical system further comprises a planar reflective optical element located between the first lens group and the first optical element; the planar reflective optical element reflects the image light refracted by the first lens group to the first optical element, the first optical element reflects the image light to the second optical element, and then transmits the image light reflected by the second optical element to the human eye; the angle between the first lens group and the first optical element is λ₂, and λ₂ satisfies following relation (17): 60°≤λ₂<180°  (17).
 15. The reflective eyepiece optical system according to claim 1, wherein the second optical element comprises two coaxial optical surfaces of the same face shape.
 16. The reflective eyepiece optical system according to claim 1, wherein the first lens group comprises one or more even-order aspherical face shapes; and both optical surfaces of the second optical element are even-order aspherical face shapes.
 17. The reflective eyepiece optical system according to claim 16, wherein the even-order aspherical face shapes satisfy relational expression (18): $\begin{matrix} {Z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {\alpha_{2}r^{2}} + {\alpha_{4}r^{4}} + {\alpha_{6}r^{6}} + {\ldots\mspace{14mu}.}}} & (18) \end{matrix}$
 18. The reflective eyepiece optical system according to claim 1, wherein the material of the second optical element is an optical plastic material.
 19. A head-mounted near-to-eye display device, comprising a miniature image displayer, wherein it further comprises the reflective eyepiece optical system according to claim 1; and the eyepiece optical system is located between the human eye and the miniature image displayer.
 20. The head-mounted near-to-eye display device according to claim 19, wherein the miniature image displayer is an organic electroluminescent device. 